linux-kernel - Re: [PATCH v15 4/4] kasan: use MAX_PTRS_PER

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Date:   Sun, 20 Jun 2021 14:17:57 +0300
From:   Andrey Konovalov <andreyknvl@...il.com>
To:     Daniel Axtens <dja@...ens.net>
Cc:     LKML <linux-kernel@...r.kernel.org>,
        Linux Memory Management List <linux-mm@...ck.org>,
        kasan-dev <kasan-dev@...glegroups.com>,
        Marco Elver <elver@...gle.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        linuxppc-dev@...ts.ozlabs.org, christophe.leroy@...roup.eu,
        aneesh.kumar@...ux.ibm.com, bsingharora@...il.com
Subject: Re: [PATCH v15 4/4] kasan: use MAX_PTRS_PER_* for early shadow tables

On Thu, Jun 17, 2021 at 12:30 PM Daniel Axtens <dja@...ens.net> wrote:
>
> powerpc has a variable number of PTRS_PER_*, set at runtime based
> on the MMU that the kernel is booted under.
>
> This means the PTRS_PER_* are no longer constants, and therefore
> breaks the build. Switch to using MAX_PTRS_PER_*, which are constant.
>
> Suggested-by: Christophe Leroy <christophe.leroy@...roup.eu>
> Suggested-by: Balbir Singh <bsingharora@...il.com>
> Reviewed-by: Christophe Leroy <christophe.leroy@...roup.eu>
> Reviewed-by: Balbir Singh <bsingharora@...il.com>
> Reviewed-by: Marco Elver <elver@...gle.com>
> Signed-off-by: Daniel Axtens <dja@...ens.net>
> ---
>  include/linux/kasan.h | 6 +++---
>  mm/kasan/init.c       | 6 +++---
>  2 files changed, 6 insertions(+), 6 deletions(-)
>
> diff --git a/include/linux/kasan.h b/include/linux/kasan.h
> index 768d7d342757..5310e217bd74 100644
> --- a/include/linux/kasan.h
> +++ b/include/linux/kasan.h
> @@ -41,9 +41,9 @@ struct kunit_kasan_expectation {
>  #endif
>
>  extern unsigned char kasan_early_shadow_page[PAGE_SIZE];
> -extern pte_t kasan_early_shadow_pte[PTRS_PER_PTE + PTE_HWTABLE_PTRS];
> -extern pmd_t kasan_early_shadow_pmd[PTRS_PER_PMD];
> -extern pud_t kasan_early_shadow_pud[PTRS_PER_PUD];
> +extern pte_t kasan_early_shadow_pte[MAX_PTRS_PER_PTE + PTE_HWTABLE_PTRS];
> +extern pmd_t kasan_early_shadow_pmd[MAX_PTRS_PER_PMD];
> +extern pud_t kasan_early_shadow_pud[MAX_PTRS_PER_PUD];
>  extern p4d_t kasan_early_shadow_p4d[MAX_PTRS_PER_P4D];
>
>  int kasan_populate_early_shadow(const void *shadow_start,
> diff --git a/mm/kasan/init.c b/mm/kasan/init.c
> index 348f31d15a97..cc64ed6858c6 100644
> --- a/mm/kasan/init.c
> +++ b/mm/kasan/init.c
> @@ -41,7 +41,7 @@ static inline bool kasan_p4d_table(pgd_t pgd)
>  }
>  #endif
>  #if CONFIG_PGTABLE_LEVELS > 3
> -pud_t kasan_early_shadow_pud[PTRS_PER_PUD] __page_aligned_bss;
> +pud_t kasan_early_shadow_pud[MAX_PTRS_PER_PUD] __page_aligned_bss;
>  static inline bool kasan_pud_table(p4d_t p4d)
>  {
>         return p4d_page(p4d) == virt_to_page(lm_alias(kasan_early_shadow_pud));
> @@ -53,7 +53,7 @@ static inline bool kasan_pud_table(p4d_t p4d)
>  }
>  #endif
>  #if CONFIG_PGTABLE_LEVELS > 2
> -pmd_t kasan_early_shadow_pmd[PTRS_PER_PMD] __page_aligned_bss;
> +pmd_t kasan_early_shadow_pmd[MAX_PTRS_PER_PMD] __page_aligned_bss;
>  static inline bool kasan_pmd_table(pud_t pud)
>  {
>         return pud_page(pud) == virt_to_page(lm_alias(kasan_early_shadow_pmd));
> @@ -64,7 +64,7 @@ static inline bool kasan_pmd_table(pud_t pud)
>         return false;
>  }
>  #endif
> -pte_t kasan_early_shadow_pte[PTRS_PER_PTE + PTE_HWTABLE_PTRS]
> +pte_t kasan_early_shadow_pte[MAX_PTRS_PER_PTE + PTE_HWTABLE_PTRS]
>         __page_aligned_bss;
>
>  static inline bool kasan_pte_table(pmd_t pmd)
> --
> 2.30.2
>

Reviewed-by: Andrey Konovalov <andreyknvl@...il.com>